The largest ever operation to wipe out invasive rodents is underway in the Galapagos Islands, where officials hope to kill 180 million rats with a poison that will not harm native wildlife.


First introduced to the islands in the 17th century, the voracious black rats and Norway rats have overrun the ecosystem and taken a devastating toll on the reptiles, birds and plants of the Galapagos. Dozens of species, most of which exist nowhere else in the world, have become critically endangered. Some species, including a native Galapagos rodent called the Santa Cruz mouse, have even been driven into extinction by the invaders.


Juan Carlos Gonzalez, a specialist with the Nature Conservancy, told the Associated Press that rats are "one of the worst problems the Galapagos have." The invasive rodents reproduce four times a year and "eat everything," he said.


This is the second phase of the rodent eradication project, which began in 2011 following a pilot project in 2008. In this phase, a helicopter will be used to drop 22 tons of poison onto Pinzon Island and Plaza Sur islet. According to the AP, there are 180 million rats on the seven-square-mile Pinzon Island, or an astonishing one rat per square foot. Plaza Sur inlet is much smaller, just 24 acres in size.


The special poison for this "raticide" was developed in the U.S. by Bell Laboratories. The small blue cubes give off an aroma that is attractive to rats but repulsive to native wildlife. The poison dissolves after about a week and new doses will be dropped on the islands on a weekly basis through the end of the month. Even the rats that ingest the poison won't be a danger to the environment, as the toxin contains a special substance that will cause the rodents' bodies to quickly dry up and decay. All the same, several dozen native hawks and iguanas were captured from the island and will be kept safe until they are re-released early next year.


Phase I of this project carried a price tag of about $1 million. This phase will cost about $1.8 million. The Galapagos National Park Service, which is run by the government of Ecuador, is funding the operation in association with several nonprofits. "This is a very expensive but totally necessary war," Gonzalez told the AP.


The project needs to kill every rat on the islands in order to protect the native fauna and flora. "If we miss even one pregnant female, it won't succeed," Linda Cayot, science adviser for the Galapagos Conservancy, told the Guardian. Teams will monitor the island for a year to make sure that the rat population does not return.


The full rat eradication project will run through the year 2020. The poison will be used on uninhabited islands first before being used on the islands where people also live.


Also on MNN:

Galapagos to poison 180 million rats
Invasive black rats threaten the endangered wildlife of the Galapagos Islands.